Improve description of system.proxy_file_chmod setting

static/defaults.config.php

@@ -571,8 +571,8 @@ return [
 		// Timeout in seconds for fetching the XRD links.
 		'xrd_timeout' => 20,
 
-		// proxy_file_chmod (Octal Integer)
-		// Access rights for downloaded files in /proxy/ directory like 0640
+		// proxy_file_chmod (Octal Integer like 0640)
+		// If set, defines the files permissions for downloaded files in the /proxy/ directory, default is system-dependent
 		'proxy_file_chmod' => 0,
 	],
 	'experimental' => [